Changing 4 Speed Gear Oil Today in My '81
06-14-2014, 04:01 AM
#1
Heel & Toe
Thread Starter
Changing 4 Speed Gear Oil Today in My '81
It was suggested that I use GL-4 Gear oil. Chiltons says to use GL5. I have both...think I should go with the GL-4. Will that be ok ? Thanks, Ray
06-14-2014, 08:14 AM
#2
Nam Labrat
Member Since: Sep 2013
Location: New Orleans Loo-z-anna
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I did a Search and found this from years ago.......
Wait for other members to give more advice....since the thread started the usual debate.
From what I understand, you do not want to use a GL5 gear oil in your old Muncie (or B-W) tranny. The GL5 has things in it which are not kind to the sychros. I finally found some of the correct GL4 gear lube at NAPA. It was called Sta-Lube, and it was only in half-gallon containers.
The GL5 is fine for your differential, (no brass parts) but not your tranny.
Rich
The GL5 is fine for your differential, (no brass parts) but not your tranny.
Rich
Last edited by doorgunner; 06-14-2014 at 08:25 AM.
06-14-2014, 08:39 AM
#3
Heel & Toe
Thread Starter
Thanks, I found Brad Penn "Classic" Multi Purpose GL-4 80W90 Gear oil. All looks good with the exception of the following which is on the label: Not for use in applications requiring API GL-5 quality extreme pressure lubricants or where OEM specialized fluids are mandated. This is why I'm concerned.
06-14-2014, 09:15 AM
#5
Melting Slicks
Isn't this what your 81 chassis manual calls for? if it has been working for the last 33 years why not continue using the recommended fluid. :
06-14-2014, 12:06 PM
#6
Heel & Toe
Thread Starter
06-14-2014, 09:48 PM
#8
Safety Car
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I used the NAPA STA-LUBE GL4 in my 68 Muncie.
It's been in there since 2012 w/o any issues.
I also used it in my rear with the GM brand additive.
Again no issues.
Worse part of the job was siphoning out the old stuff.
Goes back in pretty easy with a hand pump on the bottle.
Gravity works in your favor on the refill
Marshal
It's been in there since 2012 w/o any issues.
I also used it in my rear with the GM brand additive.
Again no issues.
Worse part of the job was siphoning out the old stuff.
Goes back in pretty easy with a hand pump on the bottle.
Gravity works in your favor on the refill
Marshal
06-15-2014, 12:02 AM
#10
Depending on who you talk to you will get various recommendations on what to put in a Muncie anywhere from GL4, GL5, ATF, MTL and that will change also depending on cast or aluminum case. I stuck with GL4 because I didn't want to mess up my synchros and the 81 may be made of a different material.
06-15-2014, 08:50 AM
#11
Heel & Toe
Thread Starter
Depending on who you talk to you will get various recommendations on what to put in a Muncie anywhere from GL4, GL5, ATF, MTL and that will change also depending on cast or aluminum case. I stuck with GL4 because I didn't want to mess up my synchros and the 81 may be made of a different material.
06-15-2014, 11:06 AM
#12
Racer
Lub
Correct. I went with the GL4 because I didn't want to mess up the the synchros in my 81. Just about everyone that I discussed this with said that the GL4 is clearly the better choice regardless of what Chiltons says...better for the synchros and smoother shifting. The Brad Penn GL4 is now in there based on this.
06-15-2014, 11:03 PM
#13
Melting Slicks
Last friday I took my car out for a test drive after changing over from a TH400 to a BW Super T10. The forum member from whom I purchased the BW Super T10 had it rebuilt and let it sit as his spare.
I used Redline MTL as the initial fill. The trans shifted ok, but was noisy and started getting hot. After about 20 minutes of this I just felt something wasn't right and parked the car to avoid damaging the trans.
The next day I picked up some Brad Penn Classic GL4 at half the price of the Redline MTL and drained the water like Redline MTL. What a difference with the Brad Penn Classic GL4. The trans is now smoother, much quieter and is running cool.
I think you made a good choice with the Brad Penn product.
I used Redline MTL as the initial fill. The trans shifted ok, but was noisy and started getting hot. After about 20 minutes of this I just felt something wasn't right and parked the car to avoid damaging the trans.
The next day I picked up some Brad Penn Classic GL4 at half the price of the Redline MTL and drained the water like Redline MTL. What a difference with the Brad Penn Classic GL4. The trans is now smoother, much quieter and is running cool.
I think you made a good choice with the Brad Penn product.